1. Field of the Invention
The present invention relates to an X-ray imaging system of the nonintegrated type having an X-ray head or radiator containing an X-ray source for generating an X-ray beam, the head being rotatable for orienting the X-ray beam in space, and a planar X-ray imaging device having no mechanical connection with the X-ray head.
2. Description of the Prior Art
In X-ray examinations of patients it is important for the X-ray beam which is emitted from the X-ray source to strike the X-ray film or other planar imaging device, such as a digital image receiver, at the correct angle after passage through that part of a patient that is to be radiographed, so that the resultant image is un-distorted. To achieve this it is important that the imaging device and X-ray head be properly orientated relative to each other (usually so that a central ray from the X-ray source strikes the imaging device perpendicular to the plane of its imaging surface). A known mobile X-ray imaging system, such as that described in the brochure MOBILETT(trademark) Plus HP xe2x80x9cInstructions for Usexe2x80x9d of the company Siemens-Elema AB, is used with a film cartridge (or cassette) which has no mechanical connection with the X-ray head. This film cartridge is placed under the patient, often under the mattress on which the patient rests, and an operator is able to rotate the X-ray head around two mutually perpendicular rotational axes until the X-ray source and the cartridge are properly orientated with respect to one another.
To facilitate this orienting it is known from the MOBILETT to provide a head angle sensor having a ball, movable in an arcuate ball-race (or groove) and overlaid with a see-through display having angles marked on its surface corresponding to angles of inclination of the head from the horizontal. The actual angle of inclination of the head is indicated by the visual correspondence of ball and an angle mark. This means that in order to achieve an accurate reading of the angle from the display the operator must be standing substantially directly in front of the display. Such an angle sensor is placed on each of two mutually perpendicular outer wall sections of the X-ray head to respectively measure the degree of rotation of the head with respect to the horizontal around each of the two mutually perpendicular rotational axes. In use, an operator measures the angle of inclination (desired angle) of the planar imaging surface to the horizontal around each of a pair of axes corresponding to the rotational axes of the X-ray head and then, with the aid of the angle sensors, inclines the head to the same degree so that the central ray of the X-ray beam is perpendicular to the planar imaging surface of the imaging device.
One problem with such an arrangement is that the angle information is displayed at two separate viewing stations, perpendicular to one another. This means that the operator cannot see angle information for both angles of inclination of the X-ray head at the same time and must move around the imaging system to verify each of the angles of inclination of the head. Furthermore the operator must remember the desired angles which only adds to the burden of the operator when setting up the system.
As used herein the term xe2x80x9cviewing stationxe2x80x9d means a region of or on the external surface of X-ray imaging system at which one or more displays are situated with the intention to be viewable from a single operator location.
An object of the present invention is to provide an x-ray imaging system which avoids the above-discussed problem of inclination information being displayed at separate viewing stations which are not simultaneously observable.
The above object is achieved in accordance with the principles of the present invention in an x-ray system having an x-ray head containing an x-ray source which emits an x-ray beam, the head being rotatable around a number of axes for orienting the emitted x-ray beam in space, and having a number of head angle sensors located with the x-ray head, respectively for the different axes, which measure an angle of inclination of the x-ray head dependent on the rotation around the associated axis, each head angle sensor being connected to a display for displaying angle information related to the measured angles, and wherein each head angle sensor provides an output signal indicative of the measured angle, the display receiving these output signals and providing a graphic display of the angle information for each head sensor together at a single viewing station.
By providing angle sensors, such as accelerometers or inclinometers, which each have an output signal dependent on the sensed angles, then respectively associated displays which provide a graphic display of angle information dependent on the output signal can be readily allocated together at a single viewing station, independent of the location of the angle sensors.
Preferably, a difference former is provided which generates a signal indicative of a difference between the angle measured by each sensor and a corresponding desired angle of inclination, for example entered by an operator via a user interface such as a keypad or entered automatically from angle sensors at the X-ray imaging device, for supply to and use by the displays to provide a visual indication of the differences.